Mechanistic insights from atomically precise gold nanocluster-catalyzed reduction of 4-nitrophenol

A trio of thiolate-protected atomically precise gold nanoclusters, [Au23(S-c-C6H11)16]-, Au24(SCH2pHtBu)20 and [Au25(SCH2CH2pH)18]-, are utilized as catalysts for 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP). Despite nearly identical sizes (~1 nm), the three nanoclusters possess distinctly different atomic packing structures and surface ligand binding modes, which contribute to different catalytic performance. The [Au23(S-c-C6H11)16]- nanocluster shows the highest activity with a kinetic rate constant of 0.0370 s−1, which is higher than those of Au24(SCH2pHtBu)20 (0.0090 s−1) and [Au25(SCH2CH2pH)18]- (0.0242 s−1). Such a trio of gold nanoclusters indicate that the atomic packing mode and electronic structure play a crucial role in determining their catalytic performance.